What are your guys thought on converting the SRT to E-85? I know it will take more fuel but I do have a 255 and 750's for my 50 trim. I have not read much but I do like the idea of the cheaper fuel (even thho mpg is less) and higher octane. Discuss.

punkrokdood

08-01-2018, 12:28 PM

will not work without a standalone of sorts... POSSIBLY could work with a re-flashed PCM, but i dunno how much adjustability there would be in it

i know the SRT-4's NGC tries to maintain a stoichiometric 14.7:1 a/f ratio for gasoline at idle/ part throttle.... when running E-85 stoichiometric is more like 10:1, and the PCM will NOT let you run that rich, bigger injectors or not. at WOT, it can be tuned like you would tune any other big turbo set up, but you'd need to run a LOT richer than you do with gasoline... tuning to lambda here is a good idea to make things easier. .75-.85 lambda is generally considered a "Safe" full boost A/F ratio

i guarantee, if you run straight E-85, bigger injectors or not, you'll never see a lambda of 1 with the stock PCM

AdictedToPoker

08-01-2018, 12:44 PM

srtforums.com/forums/showthread.php?t=374195&highlight=ethanol

The guy in that thread claims that he used a product from here (change2e85.com/servlet/StoreFront) and the unit tells the comp what fuel to run throughout.

punkrokdood

08-01-2018, 12:58 PM

i'd really need to see how a $10 box is converting a car to run E-85, especially when it comes to a turbo vehicle...

bottom line, the only safe way to do it is with a standalone IMO

Pr3mium Brewed

08-01-2018, 12:59 PM

lol i cant even stand to read threads on that site.

AdictedToPoker

08-01-2018, 01:00 PM

i'd really need to see how a $10 box is converting a car to run E-85, especially when it comes to a turbo vehicle...

bottom line, the only safe way to do it is with a standalone IMO

Damn, I want to convert, but I dont want to drop the cash for a s/a.

punkrokdood

08-01-2018, 01:03 PM

Damn, I want to convert, but I dont want to drop the cash for a s/a.
i've considered it... and if i went with a standalone, i'd at least make a map for E85. i'm just really really skeptical about a $10 box converting it. on some cars it may be fine, but i'm guessing its just some circuitry that trick the computer into running more fuel, which is potentially disastrous

AdictedToPoker

08-01-2018, 01:05 PM

i've considered it... and if i went with a standalone, i'd at least make a map for E85. i'm just really really skeptical about a $10 box converting it. on some cars it may be fine, but i'm guessing its just some circuitry that trick the computer into running more fuel, which is potentially disastrous

i hear ya

blackbird

08-02-2018, 06:48 AM

You never want to run any methanol in a car not designed for it. Ethanol is not nearly as bad and it won't kill anything anywhere near as soon as methanol but there's more to doing a full conversion than changing injectors. The fuel pump is submerged in the fuel in addition to pumping it and needs to be specifically designed for ethanol. You'd want to check with Walbro on the compatibility. There are also a lot of seal and other system component changes when a vehicle is designed for E85 compatibility. The few people running it in their SRT-4 right now probably won't see any issues but give it time. Especially on a big turbo car relying on fueling you don't want something to die under high boost.

The ethanol does have a much higher knock resistance rating but the energy content per gallon is pretty poor which is why you need to dump a lot more fuel in. Most of the OEM systems have a sensor in the tank that is used to measure the alcohol content and tell the PCM what the content of ethanol to gasoline is so it can compute how much fuel to run. Some of the new GM systems have figure a way to remove that sensor which is probably one of the main reasons they're added the capability to so many cars (i.e. very cheap with little extra cost and can be used as a selling point and to appease the environmentalists).

Let's say you went through the fueling system and upgraded all components as needed. Our engines are going to behave a little differently than a naturally aspirated Neon in that we have boost to deal with, and how much boost will determine how much fuel needs to be injected while a n/a car is a lot more linear in its fuel needs.

i know the SRT-4's NGC tries to maintain a stoichiometric 14.7:1 a/f ratio for gasoline at idle/ part throttle.... when running E-85 stoichiometric is more like 10:1, and the PCM will NOT let you run that rich, bigger injectors or not. at WOT, it can be tuned like you would tune any other big turbo set up, but you'd need to run a LOT richer than you do with gasoline... tuning to lambda here is a good idea to make things easier. .75-.85 lambda is generally considered a "Safe" full boost A/F ratio

i guarantee, if you run straight E-85, bigger injectors or not, you'll never see a lambda of 1 with the stock PCMI'd have to think about it a little more, but the stock PCM should be looking only at Lambda when trying to maintain stoich at idle and light cruise. All O2 sensor measure in Lambda and that's probably what the NGC uses in it's calculations. A/F or AFR is nothing more than taking that Lambda number and multiplying it by a conversion factor to give the ratio for a specific fuel type. Lambda is Lambda and if the NGC is using that you can burn whatever you want and it will always remain the same (Lambda of 1=stoich=all fuel burnt and essentially no leftover oxygen). The AFR is just a number to make it easier for us humans to grasp how much air to fuel an engine is using.

The problem does come down to tuning. Like mentioned converting a naturally aspirated car is much easier since you might be able to just mechanically increase the fuel flow with injectors or fuel pressure. On the SRT-4 it's still going to need more fuel at idle and it will also need the extra fuel under load but you would need some tuning solution to maximize the gains. Another thing to consider is how readily available it is in your area. If you travel to a lot of areas that don't have ethanol/E85 you'd have to be able to switch fuel maps and mixing different amounts (such as refilling on gasoline while still having a few gallons E85 in the tank) might cause issues if you go into boost.

Pr3mium Brewed

08-02-2018, 08:50 AM

If I knew as much as blackbird I think I'd have a headache and a nose bleed all the time.

blackbird

08-02-2018, 09:04 AM

I just took a look at the other thread on the other site and went to the web site that's selling the "conversion" device. After looking at the installation procedures and how it only plugs in between the injectors I'm guessing it has a DSP that receives the injector signal and adds a predetermined amount of pulse-width that it then fires the injectors a little longer. I shot them off an email asking some questions and will see what they have to say.

blackbird

08-02-2018, 09:04 AM

And I should really look into these nose bleed problems I've been having. :lulz:

punkrokdood

08-02-2018, 09:24 AM

something really really long

I guess that makes sense... i was thinking about the PCM's correction factors not compensating, but forgot to factor that in with larger injectors. now that i think about it, it could probably work... crudely, but still work. I'd have to read up more again to be able to do the math to figure "about" what size injector would be needed

el_jefe

08-02-2018, 09:27 AM

Plus E85 is only cheaper because of the govt subsidy. Plus you get crappier mileage. Have fun with that.

punkrokdood

08-02-2018, 09:32 AM

handy chart

punkrokdood

08-02-2018, 09:34 AM

Plus E85 is only cheaper because of the govt subsidy. Plus you get crappier mileage. Have fun with that.
in practice, most OBD-II turbocharged cars have gotten about a 5% increase in mileage, where-as N/A cars tend to experience about a 5% decrease... from what i've read...

punkrokdood

08-02-2018, 09:47 AM

it looks like you'd need to run RC750's@62 psi just to flow enough at idle to make up for the difference in A/F ratio, which at that pressure, you're only looking at about 300hp worth of fuel. for more than that, and you'd need larger injectors, or more injectors (port fueler type set-up)

unless of course my math is off, which it sounds like it is... 34% more flow is probably more than a 34% increase in A/F ratio

punkrokdood

08-02-2018, 10:17 AM

i think my math WAS off... that 34% increase is divided across 4 injectors (same airflow, needs 34% more fuel, 4 injectors are supplying fuel, each needs to do 8.5% more) that means you need about 626cc's per injector, which means RC650 injectors@40 psi, which is do-able, but to make much power, you'd need to be able to adjust the pulsewidth and run bigger injectors than that... 750's would only flow enough to support "about" 330hp with 75psi static pressure... again, if my math is correct :lol:

running 8 750cc injectors in a port-fueler type set-up would do the trick